Safety apparatus



o. E. ZoDER SAFETY APPARATUS Filed June 2o, 193e March 19,1940.' j

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I SAFETY APPARATUS l 2 Sheets-Sheet 2 Filed June A:20, 1958 `Vf/ y /jy J 83 wliimf 1| I 65 B "wx/ FIGA.

Patented Mar. 19, 1940 UNITED STATES SAFETY APPARATUS Orren E. Zoder, St. Louis, Mo., assigner to J. Ray Fortune, St. Louis,vMo.

Application IJulie 20, 19.38, Serial No. 214,735 17 Claims. (Cl. 137-21) This invention relates to safety appaatus, and with regard to certain more specific-features, to safety apparatus for tanks which carry dangerous fluids such as inflammables or the like.

Among the several objects of the invention may be noted the provision of safety apparatus for automobile gasoline tanks which, when an overturning occurs (as in an accident), will prevent spilling of gasoline and thus reduce fire l0 hazards; the provision of apparatus of the class described which prevents emptying of the tank even though the gasoline feed line be broken;

a 'the vprovision of apparatus of the class described which is 4effective for any angle that the tank may assume; the provision of apparatus of this class which if fire does occur will not permit the tank to explode; and the provision of apparatus of the class described which does not interfere with the operation of providing atmospheric pressure upon the surface of the gasoline as its level lowers in the tank. Other objects will be in part obvious and in part pointed'out hereinafter.

The invention accordingly comprises the elements and combinations of elements, features of construction, and arrangements of parts which will be exemplified in the structures hereinafter described, and the scope of the application of which will be indicated in the following claims. In the accompanying drawings, in which are r illustrated several of various possible embodiments of the invention,

Fig. 1 is a diagrammatic section of a simplified form of the invention;

Fig. 2 is a diagrammatic section showing another improved form of the invention; and,

Figs. 3, 4 and 5 are vertical, enlarged and fragmentary sectionsI showing alternative constructions.

Similar reference characters indicate corre- 40 sponding parts throughout the several views of the drawings. I

Most automobile gasoline tanks today require an atmospheric vent in order that atmospheric pressure may be maintained upon the fiuid in the tank as its level lowers during use. This fact, and the fact that the gasoline line from the tank to the carburetor system often breaks in an accident, is responsible' for much loss of life and property due to spilling and firing of substantial quantities of gasoline. A further hazard at the scene of an accident occurs when fire breaks out around an otherwise safe gasoline tank. Such a tank bursts or explodes under its internal pres- 55 sure due to the bheat'. from the re, thus projecting flaming fuel to great distances. The present invention avoids these and other hazards.

Referring now more particularly to Fig. 1, there is shown diagrammatically at numeral I an automotive gasoline tank. The feed line 3 from the 5 tank leads to a carburetor pump, a vacuum tank,

or the equivalent, for drawing out fuel and forcing it to the carburetor.

The line-'3' (Fig. 1) is connected through body 2 to a pipe 5 which reaches to a point near the 10. bottom of the tank I, Where the pipe is provided with an inlet strainer 1. At the upper end of the pipe 5 is a ball-check valve 9 which is pressed to its seat by a spring II. The check valve 9 opens with flow toward the line 3 from the tank I under action of suction in the line 3. The pipe 5 is threaded into body 2 to provide adjustment of the force of spring II.

Should the line 3 break, as in an accident, and the tank turn over, the maximum pressure of the 20 liquid in the tube 5 is not enough to open the check valve 9, the spring II beingadjusted to prevent this.

At numeral I3 is shown a filling opening threaded to receive la closure cap l5 having a 25 A gasket 30. lThe cap is provided with a vent hole I1 which is normally closed by a'ball-check valve I9 which closes outwardly kunder action of the spring 2|. A threaded member 23 permits of adjusting the force of the spring to a small value 30 which is just great enough to seat the ball I9.

Under conditions of recession of. the liquid level in the tank I, the ball-check I9 will open vto admit air, as required. However, the ballcheck I9 prevents outward flow of liquid under 35- accidental overturning conditions. If the line 3 breaks or the engine stops, the valve 9 also closes.

In view of the above, it will be seen from Fig. 1 ,that all danger of leakage is avoided. At the same time, should the tank overheat, as in a fire,l the danger of explosion is avoided, because the excessive internal pressure forces liquid out past the check valve 9. It will be understood that the liquid is forced through the line 3,'if the line 3 is intact, to the carburetor where it leaks out.- It will-be understood that such leakage to a relatively safe point is preferable to an explosion, and even where the leakage adds fuel to the fire, as in the case of a broken line, this is preferable to an explosion.

In Fig. 2 is shown another form of the invention, like numerals designating like parts. In this form, the cap I5 carries no vent, and is provided with a sealing gasket 25.

The lling tube I3 is 'carried down toa point below the top of the tank I, for example, a distance of an inch and a half. The purpose of this is to provide means for preventing the complete lling of the tank and the provision of an air pocket above and around the tube 25. Thus, under excessively warm conditions, a gas cushion is obtained which prevents the large expansive forces encountered when a liquid alone is contained in an enclosed space. This feature is desirable, though not necessary to the invention, as indicated by its absence from Fig. 1

'I'he suction tube 3 leads to a valve 29 in a body 4 and the body 4 leads to a pipe 5, the latter ending near the bottom of the tank I and being covered by screen 1. In this case, the valve 29 closes outwardly and is slidably suppoted in an open spider 6. The body 4 (and hence also pipe 3) is in communication with a compartment 3I below a ilexible diaphragm 33. The valve 29 is normally pressed to its seat by a spring 35, and is moved from its seat4 to openunder reduced pressure from the suction line 3 operating upon the diaphragm 33 to pull the diaphragm down. The upper side of the diaphragm receives pressure of atmospheric degree through a pipe I connected to vent pipe 4I which preferably leads to what will be hereinafter referred to as a safe point. An outlet 8 covered by a check valve 31- communicates the space above diaphragm 33 with the interior of tank I. 'I'he valve 31 is normally held to its seat by a spring. The valve 29 is fastened to the diaphragm 33.

'I'he operation of the parts thus far described in connection with what will be called device A of Fig. 2 is as follows As soon as the engine operates, a reduced pressure is e'ected in the line 3. This causes the diaphragm to be drawn down against the spring 35. Atmospheric pressure enters over the pipe 4I. 'I'hus the valve 29 opens and uid may be drawn through the strainer 1, pipe 5, valve 29 and over the line 3 to feed the carburetor. l Should an accident occur, the engine ceases to operate, or the line 3 may break, in either of which events the tendency to a vacuum is broken under the diaphragm 3| and the spring 35 returns the diaphragm so that the va1ve29 closes and escape of liquid from the tank over line 3 becomes impossible.

If pressure builds up in the tank due to re from other sources -around the tank I, then the ball-check 31 may open under the internal pressure, and gasoline will be delivered over pipe 4I to a point which is considered normally to be safe.'

The choice of a relatively safe point is optional. The valve 31 is designed not to open until a relatively high pressure has been reached which is below the bursting point of the tank I. Ordinarily, in an accident where no re starts from other causes, this pressure-relieving action will not occur.

The above construction A takes care of the control of leakage of the contents of the tank over the line 3. To provide for venting the tank without possibility of spilling, there is provided the device B which includes a vent 39 to atmosphere via the line 4I. It is to be understood that the line 39 may vent directly to the atmosphere without connection to the line 4I and that device B may be used independently of device A.

Associated with the line 39 is an outwardly seating ball-check valve 42 which rests upon a cam 43 of lenticular form. The cam 43 has .permits inspiration of air.

associated therewith a depending Y weight 45. The cam 43 rests upon the lower surface of a pocket 41 in which are inlet openings 49. These openings are in communication with a compartment I in which swings the pendulum Weight 45. The compartment 5I communicates with the interior of the tank by means of a pipe 53 in which is a ball-check valve 55. The check valve 55/seats by gravity normally to prevent ilow from the tank to the Valve 42. A pin 51 prevents the valve 55, when lifted, from closing upwardly. Operation of the device B is as follows:

As the level of the liquid in the tank I sinks, n

under evacuation of liquid over the line 3, the pressure is reduced, which utimately necessitates drawing air in over the lines 4I, 39, valve 42, chamber 5I, and line 53 past the valve 55 which automatically opens. Thus atmospheric pressure is normally maintained upon the liquid in the tank. As long as air is owing in, as described, gasoline liquid or vapor will not ow out. On the other hand, under warm conditions, as on a warm day, when the interior vapor pressure is above atmospheric, then no atmospheric pressure is necessary on the surface of the gasoline in the tank I. Under these conditions, the valve 55 seats and prevents the escape of vapor through line 53, compartment 5I, line 39 to the vent 4I. 'Ihus the octane rating of the gasoline is conserved.

Should an accident occur wherein the tank is overturned, the ball-check valve 55 prevents flow of gasoline outwardly from the vent 4I up to about a 90 tilt of the tank. Thereafter, the ball 55 may fall open and pass fluid.

However, under the last-named conditions, the pendulum weight 45 has swung so that the cam 43, at about a 45 position of the tank, presses the ball valve 42 to its upward seat to prevent outward flow of i'luid. Thus it will be seen that the ball-check valve 55 is effective over a tilt which is great enough to include a portion of the tilting range of closure of valve 42.

The pendulum 45 is not capable of instantaneously closing the valve 4I during the early 45 period of tilting of the tank. This is in order to take care of the normal tilting activities of the vehicle during which inspiration of air into the tank is necessary. For degrees of tilt about 45, inspiration of air into the tank is neither possible nor needed, because this ordinarily is associated with an accidental condition. It will thus be seen that the valve prevents outow over a tilt of the order of 90 or so, but always T'he valve 42 permits inspiration of air over a 45 tilt and prevents loss 0f iiuid throughout all greater angles of tilt.

Thus the tank when rolled is positively proof against all leakage through the necessary air vent. In the case of the ordinary accident, the line 3 remains intact and no fire will occur if gasoline does not leak. This tank therefore is proof against fire due to leakage therefrom. If the line 3 breaks and there is no other re, it is proof against leakage of tank contents from that line, because the valve 29 automatically closes. The slight amount of gasoline that exudes from the broken line is negligible and seldom starts a dangerous fire.

It is clear that the devices A and B may operate independently. For example, the line 39 may pass to the outlet independently of line 4|.

It is also clear that the valve 31 may be eliminated entirely, if the feature of the pressure ejection of iluid under hot conditions is not-desii-ed.

Adjustment for opening pressure of the valve 31 may be effected by the threaded cap which carries the opening 8. The opening pressure of valve 29 may also be adjusted by a suitable adjusting nut threaded on valve 29, against which the spring 35 reacts.

The advantage of the Fig. 2 construction over the Fig. 1 construction is that smaller pressure in the line 3 is necessary for withdrawing fluid from the tank. This'is because of the relatively large ratio of the effective areas of the diaphragm 33 and valve 29. In the case of Fig. 1, suction pressure must be used in the line 3 which is at least equal to the liquid head which must be held by the valve 9 when the tank overturns.

In Figs. 3 to 5 are shown alternative constructions which may be substituted for the apparatus B.

Referring to Fig. 3, the vent-pipe 39 is shown as leading to a 'float tank 6I having a restricted opening 63 which communicates with the interior of the gasoline tank. The connection between the pipe 39 and the enclosure 6| is through a valve seat 65 with which cooperates a movable valve 61, thelatter resting upon an anvil 69 attached to thetop of a hollow float 1|. The float 1| is provided with peripheral beads 13 Which act as guides and reduce the binding tendency of yiioat 1| in the tank 6|.

When not buoyed up, the oat 1| rests upon a solid, relatively heavy ball 15. The ball 15 in turn rests upon a cam member 11, the latter being supported by an adjusting screw 19 which may be locked in predetermined position by a lock nut 8|. The cam 11 is formed with a conical portion 83 and a steeper conical portion 85. The

cause suction in the line 39 results in forcing down the valve 61 against the downwardly movable iloat 1|, which when oating is free of the ball 15. Or, if the liquid level in the tank is such as not to iloat the member 1|, then air may freely enter the then open valve 61. In either event air may enter.

Should the car overturn, the relatively heavy' ball 15 will roll on the conical shape 83 and wedge the float 1| against the valve 61 to close the latter. Should the car turn throughout any tendency for the float 1| to lift from the valve 61 (being then immersed in liquid) is resisted by the sinking action of the weight of the ball 15 thereon. It is to be understood that the ball 15 is of a size and density to sink the float 1| without the aid of the wedging action of the cone 83 when the tank is overturned.

In Fig. 4 is shown a form of the device B which may be associated with the filler cap I5 and consists in a vent 81 located in the body of the cap I5. ment 99. Compartment 89 in turn communicates with'the interior of the tank through an upwardly directed valve seat 9| and passages -93 and 95.

The lower open end of the compartment 89 is covered by a Huid-tight, iiexible diaphragm 91 made of a flexible substance which is not at- The vent leads into a compart.

tacked by oll or gasoline. Such substances are known under various trade names.

Over the diaphragm 91 is formed a protective grill |02.

The center of the diaphragm 91 carries a pillar 99 for supporting a ball-check valve |0| which by gravity normally is forced away from its seat 9|, but which, when the diaphragm 91 raises, is pressed to its seat by pillar 99.

Under conditions of a sinking liquid level in the tank (when upright), air is drawn through port 81, compartment 89, normally open valve seat 9|, and passages 93 and 95. The valve |0| is heavy enough not to be drawn shut by the incoming air. Should the liquid level in the tank rise too much (as sometimes it does), or should the tank overturn, the pressure of liquid on the diaphragm 91 causes the valve |0| to close on its seat 9|, and thus prevents the outow of iiuid.

Fig. 5 shows another form of the device B which may be used in the cap I5 per se. This comprises an inlet |03 which connects with passages |05, |01, |09 and the latter connecting with the inside of the tank by way of passage I3. Passages |05, |01, |09 and are arranged in a circuit, each being preferably at right angles to the other. Each passage |05. |01, |09 and has therein a ball-check valve ||5, ||1, ||9 and |2I, respectively, each valve tending to close outwardly with ilow to the atmosphere and opening inwardly with the flow from the atmosphere to the inside of the tank. Thus, any excess outside" pressure, due to the decrease in the pressure inside of the tank caused by lowering liquid level, results in the valves ||5, ||1, ||9 and |2'| opening to permit entry of air to the tank Only one of these valves is normally gravitationally held to its seat, for example, valve I2| in Fig. 5, as shown. Thus, the incoming air needs to open only one valve against gravity. On the other hand, four valves are available against the leakage of gasoline outwardly under the interior pressure. One of these is positively shut under the force of gravity, so that even a slow exudation is impossible.

Should the automobile turn over, as in an accident, at least one of the valves is closed at all times against outward leakage.

It will be noted that, although four passages |05, |01, |09 and are used, more or less may be used in a circuitous arrangement, provided they, are related so that the plurality of valves therein always has atleast one valve forced shut by gravity.

It is to be understood that if desired the ar` rangements of Figs. 4 4and 5 need not be used on the ller caps per se, and the inlets 81 and |03 respectively may be connected to pipe 4| (Fig, 2). Thus these devices may be used in association with device A of Fig. 2.

Figs. 4 and 5 also show the provision of a socket of polygonal form in the cap |5. A square form is shown in Figs. 4 and 5. The socket |23 loosely contains the square head |25 of a handle or grip |21. Then the portion |25 isl spot welded in the socket |23 by light spot welding |29 at spaced locations. -The spot welding is just enough to hold the head |25 in the socket |23, but not enough to prevent the handle |21 from being knocked out of the socket |23 if during an accident or the like the handle is bumped with a force which would normally be great enough to tear out the plug |5 with the surrounding bushing |3|. Thus the handle is connected with the plug by a frangible connection which breaks 'usA before the plug and/or its bushing could be torn out.

The socket |23 need not be polygonal but may be of other non-circular shape, such as for example oval, the portion |25 being given a similar but slightly smaller shape. The criterion is that any twisting force necessary for tightly applying the cap or removing it under unusual conditions is available, but the spot welding |29 is not depended upon for applying such necessary twisting force. On the other hand any other forces on the handle are adapted to break the spot welding |29 to release the handle. Any equivalent of spot welding may be used for the frangible fastening means |29.

An advantage of the invention is the prevention of spilling and waste of gasoline under normal changes in atmospheric temperature. For example, if a truck comes in from a run on a very cold day and enters a warm garage, the tank and its contents are cold. If the tank then be immediately filled by `make-up gasoline, it becomes lled in a relatively cool condition. Heretofore, upc-n standing, such tanks have had the cold gasoline therein expand and spill through the vent. The present invention entirely overcomes this difliculty. Thus, under normal atmospheric temperature changes, there is effected a large saving of gasoline for truck lines etc. At the same time, under conditions of abnormal temperature changes, as in a re and the like, relief of pressure and avoidance .of explosions are effected.

It will be understood thatthe spring 35 which normally biases shut the valve 29 may have its function carried out by spring action in the diaphragm 33 itself, or by arranging the parts so that gravity effects closure of the valve. Other mechanical equivalents may also be thought of. Such equivalents of the action of the spring are intended to come Within the scope of the appended claims.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As many changes could be made in carrying out the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim:

1. Safety apparatus for tanks and the -like comprising a vent line constituting communicating means between the outside and the inside of the tank, a normally open valve in said com- 'municating means', means responsive to a substantial degree of tilt of said tank for automatically closing said valve, and a check valve serially arranged in said communication and closing outwardly with respect to the vent line, said check valve being arranged to prevent outward flow during all periods of tilt during which the firstnamed valve is open.

2. Safety apparatus comprising a tank, communicating means between the exterior and the interior of the tank, serially arranged check valves in said communicating means, each of said valves closing outwardly, one of said valves being adapted to be automatically closed by gravity over a substantial degree of tilt of said tank, means for closing the other valve in response to a tilt of said tank which is different from the tilt for which the other valve is closed butv before said one valve opens, the apparatus being arranged so that all liquid which might escape from the tank through the communicating means would necessarily need to pass through both valves.

3. Safety apparatus comprising a tank, communicating means between the exterior and the interior of a tank, serially arranged check valves in saidcommunicating means and adapted to close outwardly, one of said valves being arranged to remain closed throughout tank positions up to substantially 90 of tilt, and means for closing the other valve throughout greater degrees of tilt but before said one valve opens, the apparatus being arranged so that all liquid which might escape from the tank through the communicating means would necessarily need to pass through both valves.

4. Safety apparatus comprising a tank, communicating means between the exterior and the interior of a tank, serially arranged check valves in said communicating means each being adapted to close outwardly, one of said valves being arranged normally to remain closed by gravity throughout tank positions up to a substantial degree of tilt, the other valve being normally opened by gravity, and ,means for automatically closing the last-named valve against gravity throughout greater degrees of tilt but before said one valve opens, the apparatus being arranged so that all liquid which might escape from the tank through the communicating means would necessarily need to pass through both valves.

5. Safety apparatus comprising a tank, a communicating means between the exterior and the interior of a tank, a check valve closing downvwardly and outwardly in said communicating means and arranged substantially vertically for normal closure, and a'second check valve in said= communicating means seating upwardly and outwardly, but normally gravitationally held open and means for closing the second check valve over periods of tilt of the tank before and during which the first-named check valve i's yopen, the apparatusbeing arranged so that all liquid which might escape from the tank through the communicating means would necessarily need to pass through both valves'.

6. Safety apparatus comprising a tank, a suction line and a vent line communicating with said tank, a valve in said suction line, biasing means normally to close the valve, a housing, a dia phragm dividing said housing into two compartments, said vent line communicating with one compartment and said suction line with the other, said valve and diaphragm being connected so that upon suction occurring in the suction line, atmospheric pressure in the vent line will force said diaphragm to open the valve.

7. Safety apparatus comprising a tank, a suction line and a vent line communicating with the tank, a valve in said suction line, biasing means normally to close the valve, a housing, a diaphragm dividing said housing into two compartments, said vent line communicating with one compartment and said suction line with the other, said valve and diaphragm being connected so that upon suction occurring in the suction line, atmospheric pressure in the vent line will force said diaphragm to open the valve, a branch from said vent communicating with the interior of the tank and having a second valve therein permitting flow inward, means responsive to a substantial degree of tilt of the tank for Vautomatically closing said valve, a third valve serially Ward ow during the period of tilt during arranged in said branch and closing outwardly, said third valve being arranged to prevent outwhich the second valve is normally open.

8. Safety apparatus comprising a tank, a communicating means between the exterior and the interior of a tank, a check valve in said communicating means and normally closed by gravity throughout tank positions substantially up to 90 of tilt, a second normally open valve in said cornmunicating means, and means responsive to gravity to close said second valve at a tilt of said tank which is less than substantially 90 and for tilts of the tank of more than 90, the apparatus being so arranged that all liquid which might escape from said tank through the communicating means would necessarily need to pass through both of said valves.

9. Safety apparatus for tanks and the like having a vent, an upwardly closing valve associated with said vent, a iioat below said valve adapted upon rising to close the valve, cam means below the float responsive to tilting of the tank to force the float to close the valve upon a substantial tilt of the tank, said last-named means being adapted to sink the float to close the valve when the tank is substantially upside down.

10. Safety apparatus for a tank or the like having an outward vent, comprising means forming a single circuitous passage between the vent and the interior of the tank, and a plurality of valves in said vent, said valves being arranged so that at least one is closed in any position of the tank.

11. Vent means for tanks and the like comprising a single circuitous passage, a plurality of check valves therein, saidv passage and valves being arranged so that under any tilted condition of the vent means, at least one of said valves is gravitationally closed, each valve being arranged to permit reverse flow therethrough.

12. In apparatus of the class described, a liquid-containing tank, a suction line communicating between the outside and the inside of the tank to a point below the liquid level therein, said tank having a vent communicating between the outside of the tank and the inside thereof, a valve in the suction line, a movable member, a container for the movable member arranged to receive atmospheric pressure from the vent and apply it to the member on the one-side, said member on its other side being exposed to suction-line pressure, said member being normally biased to close said valve, atmospheric pressure moving the diaphragm from its vent side to open the valve when suction-ike pressure occurs on said other side.

13. Safety apparatus comprising a tank, a suction line and a vent communicating therewith,

a valve closing outwardly in said suction line,

biasing means normally to close the valve, a housing', a diaphragm dividing said housing into two compartments, said vent communicating with one compartment and said suction line with the other, the valve and diaphragm being articulated so that upon suction occurring in the suction line atmospheric pressure through the vent will force said diaphragm to open the valve, said housing on the vent side of the diaphragm having `ing a communication with the interior of the tank, a check valve normally biased to close said communication from its diaphragm side, excessive pressure in the tank being enough to force fluid through said check valve against the vent side of the diaphragm to cause venting through said line and opening of the valve to effect further venting through the suction line.

14. Safety apparatus comprising a tank, a liquid suction line communicating with the interior of said tank, a liquid control valve in said suction line, means for normally biasing shut Vsaid valve, a housing, a movable member dividing said housing into two compartments, said suction line beconnected with one compartment, said valve and movable member being so connected that merely upon substantial suction occurring in the suction line, pressure on the other side of the movable member will always force said movable member to open the valve.

15. Safety apparatus comprising a tank, a liquid suction line communicating with the interior of said tank, a liquid control valve in said suction line, means for normally biasing shut said valve, a housing, a movable member dividing said housing into two compartments, said suction line being connected with one compartment, said valve and movable member being connected so that upon suction occurring in the suction line, pressure on the other side of the movable member will force said movable member to open the valve, and a check valve having an opening from the other of said two compartments into the tank and biased to close against predetermined pressure in the tank but to open above such pressure.

16. Safety apparatus comprising a tank, a suction line communicating with said tank from the exterior, a valve in said suction line, biasing means normally to close the valve, a housing, a movable member dividing said housing into ,two compartments, said suction line vbeing connected with one compartment, said valve and movable member beingconnected so that upon' suction occurring in the suction line, pressure on the other side of the diaphragm will force said diaphragm to open the valve, a vent line leading from the outside of the tank to said other side of the, movable member, there being also an opening between the inside of the tank and said other side, a check valve in said opening normally checking against entry of fluid to thediaphragrn but under abnormal pressure conditions in the tank permitting such entry.

17. Apparatus of the class described comprising a tank, a suction line leading into the tank, a diaphragm having one side exposed to the suction pressure in said line and adapted to be deliiected thereby, a valve adapted to open in response to diaphragm deflection, means normally to close the valve when the diaphragm is not deflected, a vent line connecting the other side of the diaphragm with the atmosphere, branch means communicating between said vent line and the interior of the tank, a valve in said branch means, and means to hold said valve to its seat in response to vapor pressure in the tank and thus to resist escape of vapor under pressure in the tank.

ORREN E. ZODER. 

